Spectrometers measure properties of light over a portion of the electromagnetic spectrum. Spectrometers usually employ a source of electromagnetic energy, and various optical devices such as mirrors and gratings as optical filters for dispersing the light to the detector, as well as a detector to detect the light intensity as a function of wavelength. Existing devices for detecting the light properties include electronic photodetectors such as photodiode arrays, charge-coupled devices (CCD) or CMOS active pixel sensor arrays.
Optical spectrometers are used to detect and quantify the characteristics or concentration of a physical, chemical or biological target object. Medical diagnostic machines using optical spectrometers allow for characterization of chemical and biological information that can be used to detect disease, track associated health markers, or identify dangerous fluid borne chemicals, using only small amounts of blood, urine, saliva, or other physical specimen. However, widespread adoption of this technology has been limited in part due to the cost and size of spectrometer equipment. Typically, only laboratories with complex testing protocols and highly skilled technicians could perform accurate spectroscopic analysis. The time required to deliver samples to the lab, along with the cost of shipping and tracking to prevent misidentification has prevented wider use of spectroscopic diagnostics, and limited the type of testing that is available.
One of the factors limiting widespread adoption of diagnostic spectrometers is the high cost of the associated specimen handling structures and filters suitable for spectroscopic analysis. Attempts have been made to provide spectrometers using low cost cuvettes that can be easily cleaned or cheaply disposed of after single use. For example, U.S. Pat. No. 8,231,268, titled “Screening system and method for analyzing a plurality of biosensors” and assigned to Corning Inc. discloses a cuvette containing system that can analyze using a grating sensor, a reflectometric interference spectroscopy (RIFS) sensor, or a surface plasmon resonance (SPR) sensor. Cuvettes useful with the system include both cuvette strips/bars and rotor cuvette systems. For example, the rotor cuvette system can be employed in combination with a 1-channel liquid handling arrangement mounted directly on a rotary axis to make it very easy to position with respect to devices for liquid handling or measurement. The typical rotor cuvette system is an injection molded article which is made from the same plastic materials as those commonly used to make microplates. Rotor cuvette system can support flow through cuvettes where each cuvette can contain a grating biosensor, an optical transducer structure, or micro-optical interferometers. This rotor cuvette system can also be optimized for measurements of absorbance, fluorescence or luminescence, and widely available from manufacturers such as Hitachi and Olympus.
Cleanable cuvettes and flow chambers for various spectroscopic applications have also been disclosed. For example, U.S. Pat. No. 5,116,759 assigned FiberChem Inc., discloses reservoir sensors for detecting and quantifying inorganic species such as cations, anions and non-ionic species; organic species and pharmaceutical products; and biological species such a viruses, bacteria, antigens and enzymes. The system encompasses a wide range of light interaction techniques and a large number of sensing chemistries. The design allows for the sensing agent to be removed, the cell cleaned and new sensing material added automatically without contamination of sample or surrounding area. Different replaceable reservoir cells can be easily inserted and removed from the sensor body. In one disclosed embodiment, a miniaturized modular reservoir sensor is produced which is easy and inexpensive to manufacture, rugged, reliable, easy to use, and reproducibly uniform. The sensor is small, typically having dimensions of length (optical path-source to detector) of 0.25″ to 1.0″, a reservoir diameter (inside) of 0.125″ to 0.5″, and a volume of 10-200 microliters. The cell body can be made of thermoplastic polymer impervious to water. A preferred light source is a high luminosity, high directivity light emitting diode (LED), with 30-40 microwatts of power.